1. Field
Embodiments of the present invention may relate to a light emitting diode (LED) based lamp.
2. Background
An incandescent lamp, a halogen lamp, a discharge lamp and/or the like have been used as a lamp. A Light Emitting Diode (LED) has also been used. LED based lamps may use an LED member as a light source. The LED member may emit a light as minority carriers injected, by using a semiconductor P-N junction structure, are generated and re-coupled again. Light from the LED member may have a wavelength that varies with kinds of impurities added thereto, thereby enabling the LED member to emit a red color, a blue color, and/or a yellow color, and to produce a white color by an appropriate combination of the colors. The LED member may be advantageous in that the LED member may have a smaller size, a longer lifetime, a better efficiency, and/or a faster response than a light source such as the incandescent lamp, and/or the halogen lamp.
If an LED based lamp is used merely for lighting, then a direction of the light may be offset by using a non-transparent diffusion cap. If the direction of the light is required for a particular purpose, a lens structure may guide the light from the LED member in a particular direction.
The LED based lamp having a directional light may have a lens unit (or lens) or a combination of a lens unit and a reflector. By using the lens unit and the reflector, light from the LED member may have a direction that is incident on a desired region.
A combination of a plurality of microlens, (i.e., a microlens array (MLA)) may be provided on a surface of the lens (i.e., on a light emission surface). The microlens array may obtain a desired light distribution, and enhance Center Beam Candle Power (CBCP). The microlens array may also collect the light once more, which may not have been properly collected at the lens unit.
FIG. 1 shows that a microlens in a microlens array may be semi-spherical. The microlens array may have problems. As shown in FIG. 2, it may be difficult for the microlens array to avoid distortion of light distribution. As shown in FIG. 3, it may be difficult for the microlens array to avoid formation of a yellow ring YR in which a portion of emitted light may look (or appear) yellow.